1. Field of the Invention
The present disclosure relates to an image heating apparatus for heating a toner image on a sheet. This image heating apparatus can be used in an image forming apparatus such as a copying machine, a printer, a facsimile apparatus, and a multifunction machine endowed with a plurality of functions of these machines.
2. Description of the Related Art
Conventionally, a fixing device (image heating apparatus) configured to fix a toner image to a recording material (sheet) has been mounted in an image forming apparatus utilizing electrophotography or the like.
Japanese Patent Application Laid-Open No. 2010-107659 discusses a fixing device using an endless fixing belt. In the case where such a fixing belt is used, there is a fear that a phenomenon will occur in which the fixing belt is deviated in the width direction thereof. In view of this, in the fixing device discussed in Japanese Patent Application Laid-Open No. 2010-107659, in order that the running range of the fixing belt may not be deviated from the normal zone, a steering roller (supporting roller) supporting the fixing belt is displaced, whereby the fixing belt is caused to remain within the normal zone.
On the other hand, Japanese Patent Application Laid-Open No. 2008-040363 discusses the problem of generation of uneven gloss in a fixed image, which is attributable to a state in which a part of the outer surface of the fixing roller has become more roughened than the other portion thereof as a result of repeated fixing process on a large number of recording materials. In view of this, in the device as discussed in the document described above, the outer surface of the fixing roller is rubbed by a rubbing roller, whereby the surface roughness of the outer surface of the fixing roller is made substantially uniform in the longitudinal direction thereof.
In this connection, the present inventor examined a configuration in which a rubbing roller is arranged, with a support roller supporting the fixing belt from the inner surface being used as an opposing member, and in which a steering roller is displaced such that the running range of the fixing belt remains within the normal zone, finding out the fact that the configuration involves the following problem.
More specifically, as the steering roller is displaced, the path of the fixing belt is changed. As a result of this change in the path of the fixing belt, a part of the fixing belt moves away from the support roller functioning as the opposing member of the rubbing roller. The present inventor has found out that when the rubbing roller is brought into contact with this part, there is involved variation in the longitudinal direction of the pressure distribution of the rubbing roller with respect to the fixing belt, which means there is a fear of the fixing belt becoming incapable of being properly rubbed.